/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.iotdb.library.dprofile;

import org.apache.iotdb.library.util.Util;
import org.apache.iotdb.udf.api.UDTF;
import org.apache.iotdb.udf.api.access.Row;
import org.apache.iotdb.udf.api.collector.PointCollector;
import org.apache.iotdb.udf.api.customizer.config.UDTFConfigurations;
import org.apache.iotdb.udf.api.customizer.parameter.UDFParameterValidator;
import org.apache.iotdb.udf.api.customizer.parameter.UDFParameters;
import org.apache.iotdb.udf.api.customizer.strategy.RowByRowAccessStrategy;
import org.apache.iotdb.udf.api.type.Type;

import java.util.ArrayList;

/**
 * This function is used to standardize the input series with min-max.
 */
public class UDTFMinMax implements UDTF {
    ArrayList<Double> value = new ArrayList<>();
    ArrayList<Long> timestamp = new ArrayList<>();
    String compute = "batch";
    double min = 0.0d;
    double max = 0.0d;
    boolean flag = true;

    @Override
    public void validate(UDFParameterValidator validator) throws Exception {
        validator
                .validateInputSeriesNumber(1)
                .validateInputSeriesDataType(0, Type.INT32, Type.INT64, Type.FLOAT, Type.DOUBLE)
                .validate(
                        x -> ((String) x).equalsIgnoreCase("batch") || ((String) x).equalsIgnoreCase("stream"),
                        "Parameter \"compute\" is illegal. Please use \"batch\" (for default) or \"stream\".",
                        validator.getParameters().getStringOrDefault("compute", "batch"))
                .validate(
                        params -> (double) params[0] < (double) params[1],
                        "parameter $min$ should be smaller than $max$.",
                        validator.getParameters().getDoubleOrDefault("min", -Double.MAX_VALUE),
                        validator.getParameters().getDoubleOrDefault("max", Double.MAX_VALUE));
    }

    @Override
    public void beforeStart(UDFParameters parameters, UDTFConfigurations configurations)
            throws Exception {
        value.clear();
        timestamp.clear();
        min = 0.0d;
        max = 0.0d;
        flag = true;
        configurations.setAccessStrategy(new RowByRowAccessStrategy()).setOutputDataType(Type.DOUBLE);
        compute = parameters.getStringOrDefault("compute", "batch");
        if (compute.equalsIgnoreCase("stream")) {
            min = parameters.getDouble("min");
            max = parameters.getDouble("max");
        }
    }

    @Override
    public void transform(Row row, PointCollector collector) throws Exception {
        if (compute.equalsIgnoreCase("stream") && max > min) {
            collector.putDouble(row.getTime(), (Util.getValueAsDouble(row) - min) / (max - min));
        } else if (compute.equalsIgnoreCase("batch")) {
            double v = Util.getValueAsDouble(row);
            if (Double.isFinite(v)) {
                value.add(v);
            }
            timestamp.add(row.getTime());
            if (flag) {
                min = v;
                max = v;
                flag = false;
            } else {
                if (v > max) {
                    max = v;
                } else if (v < min) {
                    min = v;
                }
            }
        }
    }

    @Override
    public void terminate(PointCollector collector) throws Exception {
        if (compute.equalsIgnoreCase("batch") && max > min) {
            for (int i = 0; i < value.size(); i++) {
                collector.putDouble(timestamp.get(i), (value.get(i) - min) / (max - min));
            }
        }
    }
}
